Experience with trying to get a sharp focus with an imaging camera prompted me to design a high reduction ratio system. It has been in the back of my mind to do this for some time. Using spur gears or an epicyclic gear box built into the focusing knob is not easy, as it is not an option to cut spur gears without specialized equipment that is not available to hand crafting. But cutting a worm and wheel set is. I set up simple jig to hob a worm wheel on the lathe, using a 3/8" X 11 TPI Whitworth tap as a hobbing tool. A description of this technique will be posted at a later date. I built this new system into a 2" focuser for a client who was enthusiastic about the idea. The system works very well and one turn of the fine focus wheel will advance the eyepiece tube 0.34mm at the ratio of 55:1, the wormwheel having 55 teeth. I used "Delrin" or "Acetal" for the worm wheel.

TCM please dont be put off by my CF,s I am a builder of many years experience, you go ahead and post your efforts, you have something to contribute. I will certainly take notice of what you post, and give you encouragment.

A further innovation is the fixing of the focuser shaft or pinion bracket, I decided on a floating dynamically located assembly. The bracket is held in place by the pressure of the pinion against the eyepiece tube and it locks in place. A pressure screw is used to vary this pressure. Also there is a locking screw to jam the tube when under heavy loading.The pic shews the pinion bracket partially removed from the CF body.

TCM please dont be put off by my CF,s I am a builder of many years experience, you go ahead and post your efforts, you have something to contribute. I will certainly take notice of what you post, and give you encouragment.

You are the kind of people who made it possible for me to complete my first scope recently...the encouragement from you-and-yours is splendid!